Urban greening tree species play a critical role in beautifying city environmental conditions and cleaning air, especially in arid and semi arid areas of northwestern China. To better understand the characteristics of bacterial communities loaded on the surface of typical urban greening tree species, scanning electron microscopes (SEM) and the substrate utilization profiling (BIOLOG) method were employed to evaluate the bacterial structure and functional community diversity associated with the leaves of Platanus orientalis, Robinia pseudoacacia, Prunus cerasifera, and Diospyros kaki growing in Xi’an City. The results showed that the dominated bacterial species were sphaerita and bacillus observed by SEM. R. pseudoacacia and P. cerasifera were dominated by sphaerita, but P. orientalis and D. kaki were dominated by bacillus. The BIOLOG metabolic profile results revealed that the highest Average Well Color Development (AWCD_590nm) was D. kaki, which was 4.3 times higher than that of P. orientalis (P<0.01). The AWCD value was ordered as: D. kaki > P. cerasifera> R. pseudoacacia> P. orientalis. Meanwhile, the highest species richness, species diversity, and Shannon’s diversity index were also found in D. kaki with 29, 4.79, and 3.09, respectively (P<0.05). The utilization of amino acids, carboxylic acids, carbohydrates, amines, polymers, and phenolic compounds by leaf bacteria was different. Amines and Polymers were most utilized by P. orientalis and R. pseudoacacia, respectively. Phenolic compounds were most metabolized in D. kaki. The principle component analyses (PCA) revealed that PC1 and PC2 explained 36.41% and 11.99% of the total variation, respectively. There is a significant different sole carbon source utilization image of surface bacterial functional communities associated with the leaves of P. orientalis, R. pseudoacacia, P. cerasifera, and D. kaki growing in Xi’an City. The leaf of D. kaki can maintain more bacterial functional community diversity than others, and it can be used as the pioneer city greening afforestation tree species in Xi’an City, Shaanxi Province.